Tray dryers are known for use in drying various products such as grain, ceramic materials, or coal. Tray dryers typically include a central, vertically oriented shaft to which a number of trays are attached and horizontally disposed. The central shaft and trays may be encased within an outer shell. Product to be dried is placed onto a tray that rotates due to rotation of the central shaft. A leveler arm can be attached to an inner wall of the shell or other structure next to the rotating trays. The product may contact the leveler arm and hence leveled upon rotation of the tray under the leveler arm.
The tray dryer can also include a scraper arm that with the leveler arm may be attached to the inner wall of the shell or to another structure that does not move with respect to the trays. Rotation of the tray under the scraper arm functions to scrape or hold the product in position while the tray continues to move under the scraper arm. The floor of the tray can include an opening so that further rotation of the tray will cause the opening to be under the product held by the scraper thus causing the product to fall through the opening via gravity. The product may then fall to a subsequent, lower tray and the process can be repeated. A fan can be incorporated into the tray dryer to create air flow through the device that can function to dry the product. The product can be dried over the course of its travel through the multiple occurrences of leveling, scraping, and falling. The product may be emptied into a removal conduit at the bottom of the tray dryer and subsequently processed or packaged.
Although capable of drying product, tray dryers require a powerful prime mover due to attachment of the rotating trays to the central shaft. Further, the suspension of trays from the central shaft requires supporting structures such as ribs be present to prevent bending thus decreasing the number of trays that can be used in a given height. Also, air flow through the tray dryer is effected in a random manner without deliberate movement of the air or optimization of the drying function of the air on the product. As such, there remains room for variation and improvement within the art.
Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the invention.